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The use of hazardous chemicals such as methyl isocyanate can be a significant concern to the residents of communities adjacent to chemical facilities, but is often an integral, necessary part of the chemical manufacturing process. In order to ensure that chemical manufacturing takes place in a manner that is safe for workers, members of the local community, and the environment, the philosophy of inherently safer processing can be used to eliminate or reduce the hazards associated with chemical processing. However, the concepts of inherently safer process analysis have not yet been adopted in all chemical manufacturing plants. This report develops a framework to guide plant managers through the process of developing an inherently safer chemical manufacturing system.

Key Messages

Although claimed to be an integral process safety management component, inherent safety considerations are incorporated into Bayer's process safety management efforts in an implicit manner that is dependent on the knowledge base of the individual facilitating the particular activity (e.g. process hazard analysis).

Bayer and its predecessors did seek to reduce risks associated with MIC, and those efforts did incorporate some aspects of risk reduction associated with inherently safer process principles. However, Bayer did not make statements or provide documentation indicating that it had engaged in a systematic effort to incorporate inherently safer processes into the decision making process.

Bayer and its predecessors evaluated trade-offs among the alternatives, but while analysis provides a very useful starting point for a comparison of technologies, it excludes factors that may be important in the decision, from the perspective of both the company and the community.

Bayer CropScience did perform Process Safety assessments, however, Bayer and the legacy companies did not perform systematic and complete inherently safer process assessments on the processes for manufacturing MIC or the carbamate pesticides at the Institute site. Bayer and the previous owners performed hazard and safety assessments and made business decisions that resulted in MIC inventory reduction, elimination of aboveground MIC storage, and adoption of various passive, active and procedural safety measures. However, these assessments did not incorporate in an explicit and structured manner, the principles of minimization, substitution, moderation and simplification. The legacy owners identified possible alternative methods that could have resulted in a reduction in MIC production and inventory, but determined that limitations of technology, product purity, cost, and other issues prohibited their implementation.

Inherently safer process assessments can be a valuable component of process safety management. However, the view of what constitutes an inherently safer process varies among professionals, so the chemical industry lacks a common understanding and set of practice protocols for identifying safer processes.

Consistent application of inherently safer process strategies by a company has the potential to decrease the required scope of organizational emergency preparedness programs by reducing the size of the vulnerable zones around its facilities. Such reductions are achieved by reducing the toxicity of the chemicals being used or produced, the quantity of the chemicals being stored, and the conditions under which they are being stored.

As currently performed, a potential concern with using inherently safer process analysis is that it may become focused too narrowly, and as a consequence, may overlook certain outcomes. Even when multiple outcomes are recognized, they may be inappropriately weighted.

The committee recommends that the Chemical Safety Board or other appropriate entity convene a working group to chart a plan for incorporating decision theory frameworks into inherently safer process assessments. The working group should include experts in chemical engineering, inherently safer process design, decision sciences, negotiations, and other relevant disciplines. The working group should identify obstacles to employing methods from the decision sciences in process safety assessments. It should identify options for tailoring these methods to the chemical process industry and incentives that would encourage their use.

The principles of inherently safer process assessment can be used to good effect in conducting an incident investigation when the objective is the prevention of potential incidents having similar fundamental, underlying (root) causes.